The objectives of the research using Ferrosilicone Vascular Occlusion in Neoplasms is to produce total destruction of hypervascular neoplasms in various parts of the body where one can isolate the blood supply to the tumor from the regional blood supply to other organs. In the past, using the dog kidney and spleen as tumor models, it has been found that this objective is readily accomplished. The principles of this technique have now been applied successfully in one patient with a hypernephroma and cancer of the anterior third of the tongue. In addition, four patients with Sphenoid Wing Meningiomas have been successfully treated. In the hypernephroma case only the branches of the renal artery to the malignant tumor were occluded by the ferrosilicone and held in the vessels by the superconducting magnet until vulcanization occurred. This resulted in ischemic necrosis of the tumor that was clearly demonstrated after studying the gross specimen following immediate nephrectomy. In more recent laboratory experiments radioactive P32 has been added to the ferrosilicone solution and it has been found that radiation doses up to and exceeding 70,000 rads can be accomplished in the dog kidney and isolated segments of the dog lung. These dogs survived the procedure without apparent difficulty. The results of these preliminary experiments have been so successful that expansion of this program using other organs and different isotopes is warranted. In addition, it has been found that the technique of Ferromagnetic Silicone Occlusion can be applied to cerebral berry aneurysms by using internal and external coating. Further exploration of this technique for treatment of cerebral aneurysms and vascular malformations of the brain will be carried out.